Devices employing capabilities for detecting and sorting data collisions in transmitted signals have been known and are widely used. One example of this is implemented in systems using interrogators or read/write devices that decode data transmitted from a transponder such as, for example, radio frequency identification tags (RFID tags) used in high frequency RFID systems. In some well-known methods, existing interrogators recover and integrate a subcarrier signal modulated by a low frequency bitstream, typically yielding an original bitstream with a data rate of 26.48 kb/s. This low frequency bitstream is fed to a multi-bit analog to digital converter (ADC). The converted signal is decoded by a microcontroller/processor and the data then can be transmitted to a host computer. As the bitstream prior to conversion is analog (i.e. the maximum and minimum values will vary depending on variables such as transmitted radio frequency (RF) power, environmental noise and number of RFID tags in the field), it is possible with this method to determine a number of characteristics of the system, including whether a data collision has taken place, and whether variables in the system require adjustment in order to obtain optimal operating conditions.
However, existing designs and methods can require additional filtering and amplification to convert the subcarrier signal to a baseband signal. As above, the baseband signal typically is converted to a digital signal by an analog to digital converter (ADC), and the converted signal is then analyzed and the appropriate output is generated.
These additional stages for converting the signal so that it may be decoded can result in slower performance in the communication, for instance, between an interrogator and an RFID tag, and more particularly can result in slower detection of the occurrence of data collisions.
Although these devices may be suitable for their intended uses, improvements may still be made in providing a device employing data collision detection capabilities where it is not necessary to adjust the RF output power, as the desired reading range or read/write distance remains generally constant. Particularly, there is a need for a data collision detection device and method for detecting data collisions where transmitted data can be directly decoded from a recovered subcarrier signal. Further, there is a need to provide a more compact and more cost efficient design for decoding transmitted data and for detecting data collisions at an earlier stage, for instance, by eliminating the need for an analog to digital converter in such systems.